1) If the attorney took your case on contingency, you should not be on the hook for fees. While this attorney may put a lien on any recovery you pursue with another attorney, he/she usually cannot charge you directly for the case. Lawyers eat the cost of bad cases -- this is why they screen so much up-front.

2) If your claim is valid, and you have a good explanation for why the attorney withdrew, you can find other counsel. They will negotiate fees with your prior attorney.